Present manual efforts to control heat input into a coke oven require the operator to observe trends in the coke temperature as the coke is pushed, via visual determination and occasionally by hand-held pyrometer measurement. The operator is then expected to increase or decrease the heat input to the battery as required by changes in coal composition, battery operating rate, and underfiring gas composition. The inability of the operator to anticipate and make accurate underfiring adjustments results in increased fuel usage, decreased coke quality and decreased battery life.
Because of the problems with manual control systems, considerable effort has been put into automating the control of heat input into coke ovens. For example, U.S. Pat. No. 4,045,292, incorporated herein by reference, teaches a system for controlling combustion in a coke oven battery by setting a target flue temperature on the basis of details of the coal charge in order to achieve a target net coking time and a target soaking time given by a coke production schedule. The actual flue temperature is then measured and deviations from the target flue temperature are determined to set a flow rate and calorific value of the fuel gas for each oven group, and a corresponding stack draft for each oven group. The target flue temperature is then bias corrected based on the measured flue temperature, measured net coking times, measured soaking times and the details of the corresponding coal charge.
However, the system of U.S. Pat. No. 4,045,292 requires a large amount of instrumentation and related wiring to determine by indirect measurement the amount of heat needed by the oven. This tends to increase the risk of error. Such an instrumentation and wiring intensive system is very susceptible to malfunction. Such malfunction could naturally lead to expensive errors in control of heat input, expensive plant closedowns for repair, decreased coke quality, and decreased battery life.